The optimal dose of Methadone is that which allows the patient to function normally without a compelling urge to use other opiates. There is no standard milligram- per-day dose limit. The effective dose is determined by clinical response of the patient.
The maximum Methadone dose is that which allows the patient to function without symptoms of excess opiate effect. These symptoms may include prolonged constipation that is non-responsive to over-the-counter laxatives; nodding off at the peak blood concentration which is expected to occur between two and four hours after ingestion (temporality); slurred speech; inattentiveness; impaired gait; and a state of depressed activity or sedation which impairs activities of normal life. This dose is higher than the optimal dose.
The optimal dose is determined by subjective assessment of the patient. Rarely is there an objective parameter by which it can be measured. The ability of the patient to determine an appropriate dose on his own was tested and reported by Robles, et al, Journal of Substance Abuse Treatment 20:225-230, 2001. Fifty-seven patients were permitted to determine their own dose based upon their preference. A six-month interval when the physician’s approval was required for a dose exceeding 99 mg was followed by a 16-month interval of patient-regulated dose with no upper limit. Patients were required to remain on their selected dose for at least three days. The highest dose among 57 participants was an increase from 165 mg to 300 mg. The average dose changed from
76.84 to 80.04. The frequency of positive urine tests decreased from 5.26% to 1.64%.
Use of other drugs remained unchanged. There was no evidence of diversion since all participants had appropriate medication inventory when recalled. This research demonstrates that most patients after 6 months’ stabilization are more able than the physician to regulate their own Methadone dose, with a better treatment outcome as determined by urine drug monitoring.
Concern about life-threatening overdose using self-determined doses is addressed in the medical literature by report of accidental medication of stable patients with ten times their usual dose. Three such patients manifest clinical signs of excess opiate effect (citation) but did not experience impaired vital function and required no treatment.
Patients on a stable dose of Methadone who have accidentally received a double dose manifest no visible signs of opiate excess with 2-4 hours of administration. Personal experience indicates that a wide margin exists between the usual dose and the amount required to endanger vital function.